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ffmpeg / libavformat / audio.c @ 7be806f3

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/*
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 * Linux audio play and grab interface
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 * Copyright (c) 2000, 2001 Fabrice Bellard.
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 *
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 * This library is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2 of the License, or (at your option) any later version.
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 *
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 * This library is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with this library; if not, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 */
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#include "avformat.h"
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/soundcard.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/time.h>
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#define AUDIO_BLOCK_SIZE 4096
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typedef struct {
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    int fd;
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    int sample_rate;
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    int channels;
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    int frame_size; /* in bytes ! */
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    int codec_id;
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    int flip_left : 1;
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    uint8_t buffer[AUDIO_BLOCK_SIZE];
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    int buffer_ptr;
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} AudioData;
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static int audio_open(AudioData *s, int is_output, const char *audio_device)
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{
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    int audio_fd;
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    int tmp, err;
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    char *flip = getenv("AUDIO_FLIP_LEFT");
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    /* open linux audio device */
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    if (!audio_device)
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        audio_device = "/dev/dsp";
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    if (is_output)
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        audio_fd = open(audio_device, O_WRONLY);
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    else
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        audio_fd = open(audio_device, O_RDONLY);
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    if (audio_fd < 0) {
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        perror(audio_device);
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        return AVERROR_IO;
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    }
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    if (flip && *flip == '1') {
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        s->flip_left = 1;
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    }
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    /* non blocking mode */
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    if (!is_output)
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        fcntl(audio_fd, F_SETFL, O_NONBLOCK);
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    s->frame_size = AUDIO_BLOCK_SIZE;
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#if 0
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    tmp = (NB_FRAGMENTS << 16) | FRAGMENT_BITS;
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    err = ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &tmp);
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    if (err < 0) {
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        perror("SNDCTL_DSP_SETFRAGMENT");
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    }
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#endif
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    /* select format : favour native format */
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    err = ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &tmp);
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#ifdef WORDS_BIGENDIAN
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    if (tmp & AFMT_S16_BE) {
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        tmp = AFMT_S16_BE;
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    } else if (tmp & AFMT_S16_LE) {
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        tmp = AFMT_S16_LE;
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    } else {
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        tmp = 0;
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    }
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#else
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    if (tmp & AFMT_S16_LE) {
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        tmp = AFMT_S16_LE;
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    } else if (tmp & AFMT_S16_BE) {
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        tmp = AFMT_S16_BE;
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    } else {
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        tmp = 0;
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    }
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#endif
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    switch(tmp) {
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    case AFMT_S16_LE:
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        s->codec_id = CODEC_ID_PCM_S16LE;
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        break;
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    case AFMT_S16_BE:
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        s->codec_id = CODEC_ID_PCM_S16BE;
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        break;
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    default:
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        av_log(NULL, AV_LOG_ERROR, "Soundcard does not support 16 bit sample format\n");
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        close(audio_fd);
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        return AVERROR_IO;
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    }
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    err=ioctl(audio_fd, SNDCTL_DSP_SETFMT, &tmp);
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    if (err < 0) {
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        perror("SNDCTL_DSP_SETFMT");
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        goto fail;
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    }
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    tmp = (s->channels == 2);
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    err = ioctl(audio_fd, SNDCTL_DSP_STEREO, &tmp);
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    if (err < 0) {
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        perror("SNDCTL_DSP_STEREO");
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        goto fail;
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    }
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    if (tmp)
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        s->channels = 2;
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    tmp = s->sample_rate;
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    err = ioctl(audio_fd, SNDCTL_DSP_SPEED, &tmp);
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    if (err < 0) {
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        perror("SNDCTL_DSP_SPEED");
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        goto fail;
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    }
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    s->sample_rate = tmp; /* store real sample rate */
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    s->fd = audio_fd;
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    return 0;
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 fail:
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    close(audio_fd);
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    return AVERROR_IO;
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}
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static int audio_close(AudioData *s)
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{
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    close(s->fd);
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    return 0;
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}
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/* sound output support */
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static int audio_write_header(AVFormatContext *s1)
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{
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    AudioData *s = s1->priv_data;
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    AVStream *st;
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    int ret;
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    st = s1->streams[0];
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    s->sample_rate = st->codec.sample_rate;
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    s->channels = st->codec.channels;
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    ret = audio_open(s, 1, NULL);
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    if (ret < 0) {
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        return AVERROR_IO;
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    } else {
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        return 0;
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    }
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}
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static int audio_write_packet(AVFormatContext *s1, AVPacket *pkt)
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{
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    AudioData *s = s1->priv_data;
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    int len, ret;
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    int size= pkt->size;
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    uint8_t *buf= pkt->data;
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    while (size > 0) {
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        len = AUDIO_BLOCK_SIZE - s->buffer_ptr;
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        if (len > size)
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            len = size;
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        memcpy(s->buffer + s->buffer_ptr, buf, len);
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        s->buffer_ptr += len;
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        if (s->buffer_ptr >= AUDIO_BLOCK_SIZE) {
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            for(;;) {
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                ret = write(s->fd, s->buffer, AUDIO_BLOCK_SIZE);
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                if (ret > 0)
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                    break;
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                if (ret < 0 && (errno != EAGAIN && errno != EINTR))
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                    return AVERROR_IO;
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            }
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            s->buffer_ptr = 0;
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        }
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        buf += len;
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        size -= len;
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    }
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    return 0;
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}
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static int audio_write_trailer(AVFormatContext *s1)
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{
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    AudioData *s = s1->priv_data;
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    audio_close(s);
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    return 0;
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}
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/* grab support */
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static int audio_read_header(AVFormatContext *s1, AVFormatParameters *ap)
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{
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    AudioData *s = s1->priv_data;
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    AVStream *st;
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    int ret;
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    if (!ap || ap->sample_rate <= 0 || ap->channels <= 0)
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        return -1;
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    st = av_new_stream(s1, 0);
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    if (!st) {
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        return -ENOMEM;
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    }
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    s->sample_rate = ap->sample_rate;
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    s->channels = ap->channels;
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    ret = audio_open(s, 0, ap->device);
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    if (ret < 0) {
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        av_free(st);
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        return AVERROR_IO;
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    }
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    /* take real parameters */
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    st->codec.codec_type = CODEC_TYPE_AUDIO;
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    st->codec.codec_id = s->codec_id;
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    st->codec.sample_rate = s->sample_rate;
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    st->codec.channels = s->channels;
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    av_set_pts_info(st, 48, 1, 1000000);  /* 48 bits pts in us */
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    return 0;
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}
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static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
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{
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    AudioData *s = s1->priv_data;
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    int ret, bdelay;
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    int64_t cur_time;
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    struct audio_buf_info abufi;
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    if (av_new_packet(pkt, s->frame_size) < 0)
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        return AVERROR_IO;
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    for(;;) {
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        struct timeval tv;
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        fd_set fds;
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        tv.tv_sec = 0;
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        tv.tv_usec = 30 * 1000; /* 30 msecs -- a bit shorter than 1 frame at 30fps */
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        FD_ZERO(&fds);
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        FD_SET(s->fd, &fds);
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        /* This will block until data is available or we get a timeout */
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        (void) select(s->fd + 1, &fds, 0, 0, &tv);
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        ret = read(s->fd, pkt->data, pkt->size);
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        if (ret > 0)
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            break;
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        if (ret == -1 && (errno == EAGAIN || errno == EINTR)) {
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            av_free_packet(pkt);
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            pkt->size = 0;
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            pkt->pts = av_gettime() & ((1LL << 48) - 1);
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            return 0;
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        }
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        if (!(ret == 0 || (ret == -1 && (errno == EAGAIN || errno == EINTR)))) {
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            av_free_packet(pkt);
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            return AVERROR_IO;
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        }
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    }
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    pkt->size = ret;
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    /* compute pts of the start of the packet */
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    cur_time = av_gettime();
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    bdelay = ret;
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    if (ioctl(s->fd, SNDCTL_DSP_GETISPACE, &abufi) == 0) {
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        bdelay += abufi.bytes;
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    }
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    /* substract time represented by the number of bytes in the audio fifo */
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    cur_time -= (bdelay * 1000000LL) / (s->sample_rate * s->channels);
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    /* convert to wanted units */
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    pkt->pts = cur_time & ((1LL << 48) - 1);
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    if (s->flip_left && s->channels == 2) {
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        int i;
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        short *p = (short *) pkt->data;
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        for (i = 0; i < ret; i += 4) {
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            *p = ~*p;
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            p += 2;
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        }
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    }
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    return 0;
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}
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static int audio_read_close(AVFormatContext *s1)
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{
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    AudioData *s = s1->priv_data;
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    audio_close(s);
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    return 0;
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}
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static AVInputFormat audio_in_format = {
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    "audio_device",
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    "audio grab and output",
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    sizeof(AudioData),
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    NULL,
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    audio_read_header,
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    audio_read_packet,
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    audio_read_close,
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    .flags = AVFMT_NOFILE,
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};
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static AVOutputFormat audio_out_format = {
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    "audio_device",
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    "audio grab and output",
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    "",
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    "",
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    sizeof(AudioData),
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    /* XXX: we make the assumption that the soundcard accepts this format */
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    /* XXX: find better solution with "preinit" method, needed also in
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       other formats */
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#ifdef WORDS_BIGENDIAN
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    CODEC_ID_PCM_S16BE,
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#else
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    CODEC_ID_PCM_S16LE,
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#endif
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    CODEC_ID_NONE,
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    audio_write_header,
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    audio_write_packet,
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    audio_write_trailer,
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    .flags = AVFMT_NOFILE,
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};
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int audio_init(void)
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{
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    av_register_input_format(&audio_in_format);
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    av_register_output_format(&audio_out_format);
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    return 0;
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}